The best way to colonize Mars is crazier than Elon Musk's idea of dropping nukes on the planet

Right now, Mars is a frozen, lifeless, and entirely inhospitable
place.

Yet the Red Planet holds great promise, and SpaceX CEO Elon Musk
recently discussed its future with comedian and television
host Stephen Colbert.

Musk, who hopes to build a colony of
1 million people on Mars, told Colbert that there are two
ways to warm the global temperatures on Mars, which would help
transform it from a barren wasteland into a hospitable,
Earth-like planet.

The slow way is to transport greenhouse gases, like carbon
dioxide and methane, from Earth to Mars and release them into the
Martian atmosphere.

Since then, Musk has tweeted:
"Btw, not saying we *should* nuke Mars -- just layin' out a few
options …"

But unfortunately for Musk, neither of these ways are practical
or plausible, according to Christopher Impey, an astronomer at
the University of Arizona and author and co-author of over a
dozen popular science books, including "Frontiers
of Astrobiology" and "Dreams
of Other Worlds."

Luckily for us, however, there is a way. Redirect a near-Earth
asteroid toward Mars and slam it into one of the Martian poles —
or even better, redirect two asteroids and slam them into each
pole.)

The Martian poles hold the key

That's one thing Musk and Impey agree on: If we ever hope to warm
up Mars, we must target the Martian poles.

That's because the poles contain vast amounts of carbon dioxide
ice — especially during the Martian winter. But with enough
energy, you could transform that CO2 ice into its
gaseous state, an effective greenhouse gas.

If you can increase the amount of CO2 in the Martian
atmosphere enough, you'll begin to warm the planet the same way
that rising atmospheric CO2 levels are warming Earth.

Just how much energy would it take?

Impey estimated that thousands of nuclear warheads would do the
trick, or one massive impact from an asteroid.

The advantage of an asteroid impact is two-fold: It's
radiation-free and we're already designing the technology that
could, in theory, achieve such a feat.

Bombing Mars is a bad idea

Even if we could afford to launch thousands of thermonuclear
warheads to Mars, we shouldn't, Impey said.

This
artist's concept illustrates a Martian dust storm, which might
also crackle with electricity.NASA

"You [would] sort of Chernobyl-ize the whole planet," Impey told
Business Insider while explaining how the after-effects of such a
bombing would destroy any hope of colonizing Mars — even if it
grew warmer as a result. "A radioactive cloud would quickly
disperse all around Mars ... making it hazardous for anyone who
went there."

In theory, humans could still live amid the fallout as long as
they stayed inside isolated domes, like some of the Mars-like
habitats here on Earth.

But over time the radiation would seep into the Martian top soil.
This would ultimately destroy any hope of colonizing Mars because
the top soil is a critical resource for its use as building
material and also for the water it contains, which future
colonies could extract.

"You've got water, you've got oxygen, you've got building
material, [but] it's all going to be from that top soil," Impey
said. "And you just dosed the entire planet with a radiation
cloud ... impregnating the top solid, which means anyone who's
going to live on Mars in the future would have to drill or dig
down just to find uncontaminated material to work with."

Capture an asteroid and aim it at Mars

We already know how to control a rocket strapped with a nuclear
explosive, so it's easier to imagine how we might bomb Mars
rather than simply shoot an asteroid toward it.

NASA is already working on technology to capture an asteroid, but
not for the purpose of warming up Mars.

NASA's Asteroid Redirect Mission will send the first
robot in history to a near-Earth asteroid. The robot will then
collect a sample from the asteroid and place it in orbit around
the moon for astronauts to visit, study, and possibly mine by
some time in the 2020s.

And the technology NASA is designing for the ARM mission will
pave the way for future manned mission to Mars.